The use of transparent conductive coatings (TCCs) in high heat and harsh environments such as, for example, oven door applications is known. See, for example, U.S. Pat. Nos. 6,320,164; 6,235,343; 6,024,084; and 4,985,312, each of which is hereby incorporated herein by reference in its entirety. In general, a plurality of glass substrates inside the oven door helps absorb the heat generated in the interior of the oven during use and also helps reduce transmission of heat to the exterior surface of the oven door. In this regard, the TCC in an oven door helps the door to act as a heat barrier or heat sink. The ability for an oven door to act as a heat barrier or heat sink is needed in connection with self cleaning ovens, as the cook chamber of a self-cleaning oven may reach temperatures as high as 600 degrees C. during the self-cleaning process. The exterior surface of the oven door cannot reach this temperature and remain safe. For example, it is desirable to keep the exterior surface of an oven door below about 77 degrees C., more preferably below about 60 degrees C., and more preferably still lower.
While efficacious for many known layer systems, the use of sputter-coating has been known to result in mechanical durability qualities less than that achieved by known pyrolytic techniques. As a reverse function, however, sputter-coated systems often achieve better infrared reflectance than typical pyrolytic coatings. Also, sputter-coated glasses have generally been recognized as having superior optical and thermal performance characteristics than pyrolytically formed coatings, such as having improved coating uniformity, good emittance, and better solar performance characteristics.
Unfortunately, only combustion vapor deposition (CVD) pyrolytic coatings have been used for commercial oven door applications, since pyrolytic layer systems are durable enough to withstand the harsh environments of an oven including, for example, high temperatures, cleaning cycles, humidity, etc. However, it will be appreciated that if a sputter-coating technique could be devised for a particular coating system wherein the mechanical durability qualities of the sputter-coated system could approach or equal that of a pyrolytic technique, while at the same time achieving the enhanced benefits of sputter-coated technology, a significant step forward in the art would be made.
Thus, it will be appreciated that there is a need in the art for sputter-deposited layer systems that are capable of withstanding harsh environments. It also will be appreciated that there is a need in the art for sputter-deposited transparent conductive coatings (TCCs) that are capable of withstanding the harsh environments of ovens.
In certain example embodiments of this invention, a method of making a door for an oven is provided. First, second, and third substantially parallel and spaced apart glass substrates are provided, with the first substrate being provided for an interior side of the door and the third substrate being provided for an exterior side of the door. A first transparent conductive coating (TCC) is sputter-deposited on a first major surface of the first substrate, with the first major surface of the first substrate being closest to the third substrate. A second TCC is sputter-deposited on a first major surface of the second substrate, with the first major surface of the second substrate being closest to the third substrate. At least the first and second and second substrates are thermally tempered. Each said TCC is silver-based and includes a zirconium oxide protective overcoat.
In certain example embodiments of this invention, an assembly used in the creation of an oven door is provided. First, second, and third substantially parallel and spaced apart glass substrates are provided, with the first substrate being provided for an interior side of the oven door and the third substrate being provided for an exterior side of the oven door. A first sputter-deposited transparent conductive coating (TCC) is supported by a first major surface of the first substrate, with the first major surface of the first substrate being closest to the third substrate. A second sputter-deposited TCC is supported by a first major surface of the second substrate, with the first major surface of the second substrate being closest to the third substrate. Each said TCC comprises: a first barrier layer of silicon nitride provided on the second substrate, a first nickel chromium inclusive contact layer provided on the first barrier layer, a silver-inclusive conductive layer provided on the first contact layer, a second nickel chromium inclusive contact layer provided on the conductive layer, a second barrier layer of silicon nitride provided on the second contact layer, and a zirconium oxide protective overcoat provided on the second contact layer. Each said TCC has a sheet resistance of about 4 or 5 ohms/square.
The sputter-deposited transparent conductive coatings of certain example embodiments may comprise: a first barrier layer of silicon nitride provided on the substrate, a first nickel chromium inclusive contact layer provided on the first barrier layer, a silver-inclusive conductive layer provided on the first contact layer, a second nickel chromium inclusive contact layer provided on the conductive layer, a second barrier layer of silicon nitride provided on the second contact layer, and a protective overcoat comprising zirconium oxide provided on the second barrier layer.
The example embodiments described herein may be used to build an assembly or intermediate product, which may be built into an oven door, and the oven door may be built into an oven.
In certain example embodiments of this invention, a method of making a coated article comprising a coating supported by a substrate is provided. A transparent conductive coating is sputter-deposited on a first major surface of the substrate, with the transparent conductive coating comprising: a first barrier layer of silicon nitride provided on the substrate, a first nickel chromium inclusive contact layer provided on the first barrier layer, a silver-inclusive conductive layer provided on the first contact layer, a second nickel chromium inclusive contact layer provided on the conductive layer, a second barrier layer of silicon nitride provided on the second contact layer, and a protective overcoat comprising zirconium oxide provided on the second barrier layer. The same or similar transparent conductive coating may be sputter-deposited on a second major surface of the substrate. One or more of these coated articles may be built into an assembly or intermediate product, which may be built into an oven door, and the oven door may be built into an oven.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.